Rechargeable potassium-ion batteries (PIBs) show promise beyond Li-ion technology in large-scale electrical-energy storage due to the abundance and low cost of potassium resources. However, the intercalation of large-size K+ generally results in irreversible structural degradation and short lifespan to the hosts, representing a major obstacle. Here, we report a new electrochemical K+-intercalation host, tungsten disulfide (WS2), which can store 0.62 K+ per formula unit with a reversible capacity of 67 mA h g–1 and well-defined voltage plateaus at an intrinsically safe average operation potential of 0.72 V versus K/K+. In situ X-ray diffraction and ex situ electron microscopy revealed the underlying intercalation mechanism, a relatively small cell volume change (37.81%), and high reversibility of this new battery chemistry. Such characteristics impart WS2 with ultrahigh structural stability and a long lifespan, regardless of deep or fast charging. WS2 achieved record-high cyclability among chalcogenides up to 600 cycles with 89.2% capacity retention at 0.3C, and over 1000 cycles with 96.3% capacity retention and an extraordinary average Coulombic efficiency of 99.90% at 2.2C. This intercalation electrochemistry may open up new opportunities for the design of long-cycle-life and high-safety PIBs.
展开▼
机译：可充电的钾离子电池（PIB）由于钾资源丰富且成本低廉，因此在大规模电能存储中显示出超越锂离子技术的希望。然而，大尺寸K + 的插入通常会导致不可逆的结构退化和对主体的短寿命，这是一个主要障碍。在这里，我们报告了一种新的电化学K + 插层主体，二硫化钨（WS2），每个配方单元可存储0.62 K + ，可逆容量为67 mA hg相对于K / K + 的本安平均电势为 –1 和良好定义的电压平稳状态。原位X射线衍射和非原位电子显微镜揭示了潜在的嵌入机制，相对较小的电池体积变化（37.81％）和这种新电池化学的高度可逆性。不管深度充电还是快速充电，这种特性都为WS2提供了超高的结构稳定性和长的使用寿命。 WS2的硫族化物在0.3C时最多可循环600次，容量保持率达到89.2％，在1000个循环中达到96.3％的容量保持率，在2.2℃时具有99.90％的平均库仑效率，实现了创纪录的高循环性。这种插层电化学可能为设计长寿命和高安全性的PIB开辟新的机会。
展开▼
